Ceramic greenwares having an array of microchannels are formed by extrusion and then processed (i.e., dried and fired) to form ceramic articles, such as filters and catalytic converters for exhaust-producing engines and related applications. Ceramic greenwares can be formed by extruding a plasticized batch comprising ceramic-forming components, or ceramic precursors, through a die, such as a die that produces a honeycomb structure, to form an extrudate of the ceramic-forming material. The extrudate that exits the extruder is cut transversely to the direction of extrusion to form a greenware piece. The piece may itself be transversely cut into shorter pieces after drying. In some cases, the longer piece is referred to as a “log.” Extruded pieces of greenware contain water (for example, 10%-25% by weight), and the greenware needs to be dried prior to the formation of the final product (article). In some cases, the ceramic greenware needs to be dried to greater than 98% (i.e., to having less than 2% moisture content by weight).
Certain ceramic greenwares have a relatively high graphite content and are used to make articles having a higher porosity, thinner channel walls and overall lower thermal mass for fast light off. However, increased levels of graphite in the batch make the resulting ceramic greenwares challenging to dry. In particular, the microwave drying of high-graphite ceramic greenwares tends to be non-uniform and can result in overheating that can damage the greenware.